| Characteristic | Bivariate | Multivariate | ||
|---|---|---|---|---|
| RR (95% CI) | p value | RR (95% CI) | p value | |
| No. of recorded encounters | 1.03 (1.02-1.04) | < 0.0001 | 1.03 (1.02-1.04) | < 0.0001 |
| Age at first encounter | 1.06 (1.03-1.08) | < 0.0001 | 1.06 (1.03-1.10) | 0.0002 |
| Female sex | 1.18 (1.10-1.28) | < 0.0001 | 1.12 (1.03-1.20) | 0.01 |
| Mean BMI centile | 1.11 (0.91-1.36) | 0.3 | - | - |
| Obesity* | 1.07 (0.88-1.31) | 0.5 | - | - |
| Recorded family history of hypertension | 1.44 (1.02-2.05) | 0.04 | 1.26 (0.81-1.95) | 0.3 |
Note: BMI = body mass index, CI = confidence interval, RR = rate ratio. Poisson regression used to model the rate of BP screening: number of recorded BP was used as outcome, age period (duration) was used as offset. The correlation between observations in the same cluster is approximately 0.36 - therefore Generalized Estimation Equation (GEE) was used to account for clustering of outcomes within physicians. Only variables with p value < 0.05 in bivariate model were included in multivariate model (i.e., no. of recorded encouters, age at first encounter, female sex, recorded family history of hypertension).
*BMI centile > 95%.